\documentclass{standalone}
\usepackage{tikz}
\usepackage{circuitikz}
\begin{document}
\usetikzlibrary{positioning,shapes,arrows,snakes}
\definecolor{yellowish}{HTML}{FFE699}
\definecolor{grayish}{HTML}{D9D9D9} 
\tikzset{
   rect/.style={
      align=center,
      text=black,    
      minimum width=2.5cm,
      minimum height=2cm}
}
\tikzset{
   done/.style={rect, fill=grayish }
}
\tikzset{
   todo/.style={rect, fill=yellowish}
}
\tikzset{
   arrow/.style={line width=1mm}
}
\tikzset{block/.style = {draw, fill=white, rectangle,
                     minimum height=3em, minimum width=2cm},
           input/.style = {coordinate},
           output/.style = {coordinate},
           pinstyle/.style = {pin edge={to-,t,black}}
       }
\centering

\begin{tikzpicture}[auto, node distance=2cm,>=latex',font=\sffamily]   
   \node[block](tx)                          {zender};
   \node[antenna](txant) at (tx.north) {};
   \draw[snake=expanding waves] (txant.north east) -- ++(1,0);
   \node[block,right = 6cm of tx](rx)        {ontvanger};
   \node[antenna,xscale=-1] at (rx.north) {}; 
\end{tikzpicture}
\end{document}